JP3203290B2 - Digital electronic still camera and recording method on memory card - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital electronic still camera for recording image data of a still image obtained by photographing on a memory card detachable from the camera.

[0002]

2. Description of the Related Art In the past, there was an analog electronic still camera, but nowadays, a digital electronic still camera has become mainstream. An analog electronic still camera has a solid-state electronic image pickup device. A video signal representing a subject image output from the image pickup device is subjected to recording signal processing including modulation, and is then converted to a recording medium (for example, (Floppy disk). On the other hand, a digital electronic still camera converts an analog video signal into digital image data and records it in a semiconductor memory built in a memory card.

A rotating mechanism for a floppy disk and a transfer mechanism for a write / read head as in an analog electronic still camera are not required, so that the camera can be made compact and large-capacity data can be stored. The availability of smaller and smaller memory cards is thought to be a factor in the widespread use of digital electronic still cameras, but one important feature must not be overlooked. . That is, since the image (the picture representing the subject) is digitized (since it is represented by digital data), it can be handled by a so-called personal computer (PC).

[0004] Digital image data stored in a memory card can be taken into a personal computer and an image can be displayed on a display device connected to the personal computer. Various types of image processing (such as cutting out partial images, synthesizing two or more images, enlarging or reducing an image, enhancing or blurring an image, etc.) can be performed on image data captured in a personal computer.

In order to store image data representing as many frames (a large number of pictures) as possible on a memory card, image data compression processing is generally performed in a digital electronic still camera. By the data compression processing, the amount of image data representing one frame can be reduced.

One of the encoding methods of color still image data is JPEG (Joint Photographic Coding Experts Group).
p). The image data compression / decompression algorithm used in the JPEG method is ADCT (Adaptive Discrett).
e Cosine Transform). The JPEG scheme is widely used in the computer industry and is supported by many types of personal computers manufactured by many companies. This ADCT algorithm is also applied to data compression / expansion processing in a digital electronic still camera. Therefore, compressed image data obtained by imaging with a digital electronic still camera and recorded on a memory card after data compression is
Without using a memory card-dedicated player, it can be loaded into a personal computer, played back or processed, or stored in a file.

[0007] It is inevitable that the image quality is slightly degraded by compressing the image data. Therefore, in applications where high image quality is required, it is desirable to record the original image data on a memory card without compression processing.

In the JPEG system, a Lotless mode for recording all information included in the original image data is prepared (in addition to the compressed image data, a difference between the original image data and the compressed image data is additionally recorded). Unfortunately, this Lo
The method of recording image data under the thless mode is special and is not supported by widely available personal computers. Image data recorded on a memory card in this manner cannot usually be processed by a personal computer.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to a digital electronic still / data storage system capable of recording both compressed image data and non-compressed image data (original image data) on a memory card in a form compatible with an ordinary personal computer. The purpose is to provide a camera.

A digital electronic still camera with a detachable memory card according to the present invention is a standard DOS-FA readable by a plurality of types of personal computers.
Image data is written to a memory card in a T data file structure.

A digital electronic still camera according to the present invention captures a subject and creates image data representing an image of the subject. The image data creating unit adjusts white balance of the image data created by the image data creating unit. A preamplifier for generating white balance adjusted original image data, reduced image data creating means for creating reduced image data based on the original image data, data compression of the original image data according to the JPEG method, and a compressed image Data compression means for creating data, mode setting means for setting one of a compression mode and a non-compression mode, and fixed information of a JPEG header for compressed image data and fixed information of a TIFF header for original image data in advance. When the stored storage means and the compression mode are set Activates the data compression means to create compressed image data, and stores the JPEG header fixed information stored in the storage means, at least the color management information relating to the original image data, and the reduced image data created by the reduced image data creation means. The user individual information including the reduced image data and the compressed image data created by the data compression unit are formed so that a JPEG file is formed.
When the non-compression mode is set, the TIFF header fixed information stored in the storage means, at least the color management information on the original image data, and the reduced image data created by the reduced image data creation means are included. The user individual information and the original image data obtained from the preamplifier are stored in a DOS-FAT data file structure in a memory so that a TIFF file is formed.
Image data writing means for writing to a card is provided.

A memory card has a semiconductor memory built in a case and is also called a memory cartridge.
It does not matter whether the memory card is provided with other circuit elements, for example, a CPU or a display device.

As described above, the JPEG system is supported by many types of personal computers, and many types of personal computers can handle JPEG compressed image data.

Similarly, the TIF for the original image data
The F method is also a standard supported by many types of personal computers (even by personal computers from different manufacturers). Many types of personal computers can handle original image data in the TIFF format.

The DOS-FAT format, which is a data structure in a memory card, is also included in the PCMCIA standard and is standard.

The digital electronic still camera according to the present invention has a compressed mode and a non-compressed mode. Therefore, the camera user sets the compression mode and sets the JPE
Compressed image data of the G system can be obtained, and original image data of the TIFF system can be obtained by setting the non-compression mode.

The memory card on which such image data is recorded can be removed from the still camera and loaded into a personal computer for use. Compressed image data in JPEG format, original image data in TI
Since these are recorded on the memory card in accordance with the FFs, these types of image data can be read out by various types of personal computers and various types of image processing can be performed.

Thus, the digital electronic still
Original image data as well as compressed image data obtained by a camera can be used on many types of personal computers.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the electrical configuration of a digital electronic still camera.

The image pickup optical system includes a mechanical shutter (focus plane type) 22, an image pickup lens system 23, and a stop (fixed stop; not shown). The shutter 23 is driven by a shutter drive circuit 24. A light image representing a subject incident through the imaging optical system is received by a CCD (solid-state electronic imaging device) 11. CCD11 is a CCD drive circuit
Driven by 25.

A control device 20 (including a CPU) for controlling the recording of image data on a memory card 30, which will be described later, performs exposure control, focusing control, white balance control, and other controls. As with a conventional digital electronic still camera, a two-step stroke shutter release button 29
In response to the depression of the first stage, the photometry is performed, the exposure amount is determined, and the focus control is performed (photometry element,
The focus detection element, lens driving device, etc. are not shown). In response to pressing the shutter release button 29 in the second stage, C
Photographing by CD11 is performed. A so-called electronic shutter function based on drive control of the CCD 11 is used in combination with the mechanical shutter 22. A video signal representing the light image incident while these shutters are open is output from the CCD 11.

The synchronizing signal generating circuit 27 generates a clock signal, a horizontal synchronizing signal and a vertical synchronizing signal.
11, preamplifier 12, correlated double sampling circuit 13, A /
The operations of the D converter 14, the memory controller 16, the compression circuit 18, and the control device 20 are performed in synchronization with these clock signals and synchronization signals.

The CCD 11 includes a large number of light receiving elements arranged in a mosaic pattern, and R.D.
(Red), G (green), and B (blue) color filters are provided. In the arrangement of the color filters, the odd-numbered rows (horizontal direction) are GBG.
The repetition of R and the even-numbered column are the repetition of GRGB. Therefore, the primary color signals (video signals) are output from the CCD 11 on one line in the order (GBGR...) According to the color filter arrangement every pixel clock cycle.

The output signal of the CCD 11 is input to the preamplifier 12. The preamplifier 12 has a function of amplifying the output signal of the CCD 11 and a function of adjusting a color balance (white balance) during the amplification process. That is, the control device 20 determines R, R based on the output signal of the color sensor (not shown).
A signal for controlling the amplification factor for adjusting the color balance for each of the G and B primary colors is output and supplied to the preamplifier 12. In accordance with this control signal, the preamplifier 12 changes the amplification factor in accordance with the color (R, G or B) represented by the dot-sequential primary color signal input from the CCD 11 in the cycle of the pixel clock, and adjusts the white balance. Do. At such a high speed (7 MHz
(Or 14 MHz) The amplifier itself which can change the amplification factor is already known.

The point-sequential primary color signal amplified by the preamplifier 12 and adjusted in white balance is input to one A / D converter 14 via the correlated double sampling circuit 13. A
The / D converter 14 receives an input point-sequential primary color signal (GBGR ...).
Is converted into digital image data for each primary color signal at the cycle of the pixel clock.

The digital image data (dot-sequential primary color data) output from the A / D converter 14 is converted into luminance data Y and color difference data C (color difference signal R) by an RGB / YC conversion circuit 15.
−Y and BY sequential dot data) according to the following matrix operation formula.

Y = 0.3 × R + 0.59 × G + 0.11 × B R−Y = 0.7 × R−0.59 × G−0.11 × B BY − == 0.3 × R−0.59 × G + 0.89 × B

The luminance data Y and the color difference data C output from the conversion circuit 15 are temporarily stored in a memory (DRAM) 17 under the control of a memory controller 16.

This digital electronic still camera has a mode changeover switch 28 for setting any one of the compression mode and the non-compression mode to be switchable. The compression mode compresses the luminance data Y and the chrominance data according to the JPEG ADCT algorithm described above, respectively.
The compressed data is recorded on the memory card 30.
In the non-compression mode, the luminance data and color difference data (original image data) are stored in the memory card 30 without performing the above-described compression processing.
It is recorded in. The mode signal from the mode switch 28 is provided to the control device 20. The control device 20 responds to the mode set by the mode changeover switch 28,
It controls the memory controller 16 and the selector 19 and performs a process of writing image data (compressed data or original image data) to the memory card 30.

The memory controller 16 responds to the compression mode command from the control device 20 to store the image data (luminance data Y and color difference data) stored in the memory 17 in the vertical direction.
The data is read out for each block of pixels and eight horizontal pixels, and is supplied to the compression circuit 18. The compression circuit 18 compresses the image data supplied from the memory controller 16 for each block according to the ADCT algorithm. The compressed data is provided to the selector 19.

When a non-compression mode command is given from the control device 20, the memory controller 16 reads out image data (original image data including luminance data Y and color difference data C) (uncompressed data) from the memory 17 and selects the selector 19 Give to.

Header data corresponding to the set mode is input from the control device 20 to the selector 19. As described later in detail, under the control of the control device 20, compressed data or uncompressed data and header data are selected by the selector 19 according to the set mode, and the memory
This will be recorded on the card 30.

In the compression mode, the JPEG system is adopted as described above. FIG. 2A shows the format of a data file obtained by the JPEG system. The JPEG file here includes a JPEG header, compressed image data, and a final JPEG header which are conveniently divided into three types. The first JPEG header is a code representing a start of image.
The subsequent JPEG header is called application data, which contains the user's individual information. For example, color management information (parameter values used in gamma processing and white balance processing, etc.), shooting condition information (exposure amount, focal length, presence / absence of strobe light, etc.), reduced image data (decimation of original image data) (Image data representing a reduced image created by the above). Furthermore, J
Other headers according to the PEG method follow. Following these headers, image data obtained by the compression processing is arranged. Finally, J showing the end of image
A PEG header is placed.

In the uncompressed mode, the image data is T
According to IFF (Tag Image File Format). TIF
F is a standard format for image files proposed by Aldus Corporation of the United States, and is currently supported by many types of personal computers (regardless of manufacturer) as in the JPEG format. That is, many types of personal computers can handle TIFF image data.

A data file according to TIFF is shown in FIG. This TIFF file is
It is composed of an FF header, an image file directory, image file directory data, and original image data. The TIFF header contains a code representing the TIFF file. In the image file directory, the number of tags attached to various data following the image file directory is described. Thereby, the position of the original image data is also known. The image file directory data includes the individual user information such as the above-described color management information, photographing condition information, and reduced image data. These information and data are accompanied by standardized tag information. Finally, the original image data is arranged. R, G, and
The data may be B data or the above-described Y and C data (luminance data Y and color difference data C).

In both the JPEG file and the TIFF file, the user individual information is mainly stored in a dedicated reproducing device (a device for reading and reproducing image data from a memory card, excluding a personal computer as a general-purpose device). The dedicated playback device performs more appropriate image playback using the individual information. Normal personal computers often ignore this individual information and perform reproduction processing according to reproduction information (parameters such as gamma processing) preset in the personal computer.

FIG. 3 shows a data recording structure (file structure) in a memory card (semiconductor memory in the memory card). This data recording structure (logical sector arrangement) is DOS-FAT (Disk Operating System-File A).
llocation Table) According to the baest file system. This DOS-FAT format is
Personal Computer Memory Card International Associ
ation (PCMCIA) Standards, which can now be read by almost all personal computers.

The file on the memory card is divided into a header area and a data area. The size of the header area is predetermined. The data area is divided into many clusters, and data is recorded in units of clusters. One cluster is 8 Kbytes here. Each cluster is assigned a cluster number.

The header area includes a header and FAT (File All
ocation Table) and a directory. The header describes the cluster size (= 8 Kbytes).

Now, it is assumed that the file name of the JPEG file (FIG. 2A) created in the compression mode is IMAGE1 and its size is 32 Kbytes, and this JPEG file is stored in the clusters of cluster numbers 5 to 8. Shall be It is also assumed that the file name of the TIFF file (FIG. 2B) created in the non-compression mode is IMAGE2 and its size is 960 Kbytes, and this TIFF file is stored in clusters of cluster numbers 10 to 129. Shall be.

In the FAT of the header area, a chain of clusters in which such one image file is stored is described. For example, since the JPEG file of IMAGE1 is stored in clusters 5, 6, 7, and 8, the connection of these clusters is described. Instead of multiple clusters where one image file is continuous,
Even if the image data is recorded in discrete clusters, all the image data can be read by following this chain.

In the directory of the header area, for each image file stored in the data area, its file name,
File type, file attributes, file update date,
The first cluster number and file size are stored.

FIG. 4 mainly shows a procedure of a process of recording image data on a memory card by the control device 20. This process is performed after the shutter release button is pressed in the second stage.

The mode set by the mode changeover switch 28 is read (step 40). If the mode is the compression mode, the process proceeds to step 41 and subsequent steps.

The control device 20 controls the memory
The card 30 is directly accessed and its header area (FAT
And directory) (steps 41 and 51). In this embodiment, the size of the compressed data obtained by the compression processing of the image data is predetermined. Conversely, image data is compressed so as to have a predetermined data length. The size of the original image data is predetermined in accordance with the number of pixels in the CCD 11. Therefore, J created in compressed mode
The sizes of the PEG file (FIG. 2A) and the TIFF file (FIG. 2B) created in the non-compression mode are uniquely determined according to the set mode. The required number of clusters is also determined. The control device 20 accesses the header area of the memory card 30, searches for unrecorded clusters, and determines a cluster in which an image file is to be recorded. Based on this determination, data indicating a chain of clusters in the FAT is written. The control unit 20
, The file type determined by the set mode, the first cluster number determined previously, and the file size determined by the set mode are written to the directory.

The memory 21 attached to the control device 20 has JPE
Fixed information in the G header and the TIFF header is set in advance.

When the compression mode is set, the control device 20 sets the JPE set in the memory 21 in advance.
The JPEG header (start of image, application data, and other data) is created by editing the G header fixed information and other information obtained in photographing and signal processing, and the cluster determined at the end of the memory card 30 is created. Is written through the selector 19 (step 42).

During this time, a preamplifier 12, a correlated double sampling circuit 13, an A / D converter 14, an RGB / YC conversion circuit
In the step 15 and the compression circuit 18, processing of a video signal obtained by photographing and compression processing of digital image data are performed (step 43).

The control device 20 switches the selector 19 to write the compressed image data obtained by the compression processing to the cluster following the previously written header information (step S1).
44). When all compressed data is recorded, JP
An EG header (end of image) is written (step 45).

When the non-compression mode is set,
The control device 20 controls the T set in the memory 21 in advance.
By editing the fixed information of the IFF header and other information obtained by photographing and signal processing, the TIFF header, image
The file directory and the image file directory data are created and sequentially written to the predetermined cluster of the memory card 30 (step 52).

During this time, signal processing is performed in the circuits 12 to 15, and original image data is created and stored in the memory 17 (step 53). The control device 20 switches the selector 19 to store the original image data in the memory 17 into the memory controller 16.
And writes the data in the cluster of the memory card 30 following the written data (step 54).

As described above, in the compression mode, the JPEG file containing the compressed image data is used. In the non-compression mode, the TIFF file containing the original image data is used. Is written to the memory card 30 according to the following.

In steps 42 and 52, it goes without saying that the information used in the signal processing and the information set at the time of photographing are used as the color management information and photographing condition information. When the reduced image data is recorded on a memory card, the reduced image data is created from the original image data stored in the memory 17.

The writing to the header area in step 41 or 51 may be performed after the recording of the JPEG header in step 45 or the recording of the original image data in step 54. This is particularly effective when the compression ratio is predetermined in the compression mode and the size of the compressed image data differs for each image. In step 41 or 51, only the first cluster number needs to be determined.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an electronic still camera.

FIG. 2 (A) shows the format of a JPEG file,
(B) shows the format of the TIFF file.

FIG. 3 shows a data file structure of a memory card according to a DOS-FAT format.

FIG. 4 is a flowchart illustrating a procedure of a process of writing image data to a memory card.

[Explanation of symbols]

 11 CCD 16 Memory controller 17 Memory 18 Compression circuit 20 Controller (CPU) 21 Memory 30 Memory card

Claims (5)

(57) [Claims] 1. An image data generating means for capturing an image of a subject and generating image data representing the image of the subject, adjusting the white balance of the image data generated by the image data generating means, and adjusting the white balance of the original image. A preamplifier for generating data, reduced image data generating means for generating reduced image data based on the original image data, data compressing means for compressing the original image data in accordance with the JPEG method to generate compressed image data, Mode setting means for setting one of a compression mode and a non-compression mode; storage means in which fixed information of a JPEG header for compressed image data and fixed information of a TIFF header for original image data are stored in advance; If is set, the data compression means is started and the compressed image data is The JPEG header fixed information stored in the storage means, the user individual information including at least the color management information relating to the original image data and the reduced image data created by the reduced image data creation means, When the non-compression mode is set so that the JPEG file is formed with the compressed image data created by the data compression means, the TIFF header fixed information stored in the storage means and at least the original image Each of the DOS-format data is stored in the form of a TIFF file so that color management information relating to data and user individual information including reduced image data created by the reduced image data creating means and original image data obtained from the preamplifier are formed. Image data to be written to memory card in FAT data file structure Write means digital electronic still camera equipped with. 2. A digital electronic still camera having a removable memory card and writing image data to the memory card in a standard data file structure readable by a plurality of types of personal computers. Image data generating means for imaging and generating image data representing a subject image; a preamplifier for white balance-adjusting the image data generated by the image data generating means to generate white-balanced original image data A reduced image data creating means for creating reduced image data based on the original image data; compressing the original image data according to a data compression algorithm that can be handled by a plurality of types of personal computers to create compressed image data Data compression method, either compressed mode or uncompressed mode Mode setting means for setting one of them, first header fixed information in a first format for compressed image data that can be handled by a plurality of types of personal computers, and original image data that can be handled by a plurality of types of personal computers Storage means for storing second header fixed information in a second format, and when the compression mode is set, activates the data compression means to create compressed image data, and causes the storage means to The stored first header fixed information, the user individual information including at least the color management information regarding the original image data and the reduced image data created by the reduced image data creating unit, and the user created information created by the data compression unit. A file is formed according to the first format with the compressed image data, When the compression mode is set, the second header fixed information stored in the storage unit, at least the color management information relating to the original image data, and the reduced image data created by the reduced image data creation unit are stored in the storage unit. The user-specific information including the original image data obtained from the preamplifier and the
A digital electronic still camera, comprising: image data writing means for writing to a memory card so that a file according to the format is formed. 3. A digital electronic still camera in which a memory card is detachable and image data is written to the memory card in a standard DOS-FAT data file structure readable by a plurality of types of personal computers. The fixed information of the JPEG header for the compressed image data and the fixed information of the TIFF header for the original image data are set in advance, and the subject is imaged in response to the shutter release signal. Generating, adjusting the white balance of the generated image data, generating white balance adjusted original image data, creating reduced image data based on the original image data, and selecting one of the compression mode and the non-compression mode. It is determined whether or not the compression mode is set. In this case, compressed image data is obtained by compressing the generated original image data in accordance with the JPEG method, and the JPEG header fixed information, at least color management information relating to the original image data and user-created reduced image data are generated. The information and the obtained reduced image data are written to a memory card so that a JPEG file is formed. When it is determined that the non-compression mode is set, the TIFF header fixed information and at least the original image data User individual information including the color management information relating to the image and the created reduced image data, and the generated original image data as T
A method for writing image data to a memory card in a digital electronic still camera, wherein the image data is written to a memory card so that an IFF file is formed. 4. The writing of data into the header area of the memory card is performed after the JPEG header fixed information is recorded on the memory card or the original image data is recorded on the memory card. The digital electronic still camera according to claim 1. 5. A conversion circuit for generating luminance data and chrominance data from original image data generated by the preamplifier, wherein the data compression unit converts the luminance data and chrominance data generated by the conversion circuit. The storage means stores in advance the fixed information of the JPEG header for the compressed image data and the fixed information of the TIFF header for the luminance data and the color difference data. When the non-compression mode is set, the data writing means includes the luminance data and color difference data obtained from the conversion circuit and the TIF stored in the storage means.
The F-header fixed information is stored in a memory in a DOS-FAT data file structure so that a TIFF file is formed.
2. The digital electronic still camera according to claim 1, wherein the digital electronic still camera writes on a card.